Method and apparatus for securing a guide tube

ABSTRACT

A guide tube is used for guiding an instrument through a hole within tissue of a patient. The guide tube includes a cannula member defining a passage extending therethrough along an axis. The passage is operable to receive the instrument and guide the instrument through the hole within the tissue of the patient. The guide tube also includes an expansion member that is moveably coupled to the cannula member to selectively move radially between a retracted position and an expanded position relative to the axis of the cannula member. The expansion member is at least partially insertable into the hole when the expansion member is in the retracted position. The expansion member is operable to engage with a surface of the hole when the expansion member is in the expanded position.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.14/628,680 filed Feb. 23, 2015 which is a divisional of U.S. patentapplication Ser. No. 13/280,993 filed Oct. 25, 2011, now U.S. Pat. No.8,961,535 issued on Feb. 24, 2015. The entire disclosure of the aboveapplication is incorporated herein by reference.

FIELD

The present disclosure relates to a guide tube and, more particularly,to a method and apparatus for securing a guide tube.

BACKGROUND

This section provides background information related to the presentdisclosure which is not necessarily prior art.

Guide tubes are often used during surgery and other medical proceduresfor guiding instruments into and out of the patient's body. Forinstance, neurological probes are often introduced through a patient'sskull (cranium) toward a target on the brain. The probe can electricallystimulate the brain tissue for analysis thereof, and then the probe canbe removed through the same hole in the skull. A guide tube can be usedto maintain a desired trajectory of the probe during insertion andremoval from the skull. Similar guide tubes can also be used in othermedical procedures as well.

In some specific examples, the guide tube is mounted directly to anouter surface of the patient's skull, and the probe is guided along asurface of the tool to ensure the desired trajectory. In other systems,the patient's head is secured in a desired position, the guide tube is afixture that remains separate from the patient's body. The probe isoperably attached to the fixture, which guides the probe toward and awayfrom the patient.

SUMMARY

This section provides a general summary of the disclosure, and is not acomprehensive disclosure of its full scope or all of its features.

A guide tube used for guiding an instrument through a hole within tissueof a patient is disclosed. The guide tube includes a cannula memberdefining a passage extending therethrough along an axis. The passage isoperable to receive the instrument and guide the instrument through thehole within the tissue of the patient. The guide tube also includes anexpansion member that is moveably coupled to the cannula member toselectively move radially between a retracted position and an expandedposition relative to the axis of the cannula member. The expansionmember is at least partially insertable into the hole when the expansionmember is in the retracted position. The expansion member is operable toengage with a surface of the hole when the expansion member is in theexpanded position.

A method for engaging a guide tube with a surface of a hole formed intissue of a patient is also disclosed. The guide tube includes a cannulamember defining a passage extending therethrough along an axis and anexpansion member that is moveably coupled to the cannula member toselectively move radially between a retracted position and an expandedposition relative to the axis of the cannula member. The method alsoincludes inserting the guide tube into the hole while the expansionmember is in the retracted position. Furthermore, the method includesselectively moving the expansion member from the retracted position tothe expanded position to engage the expansion member with the surface ofthe hole.

Furthermore, a guide tube for guiding a neurological instrument througha hole formed within a cranium of a patient is disclosed. The hole isdefined by an inner surface. The guide tube includes a cannula memberdefining a passage extending therethrough along an axis. The passage isoperable to receive the neurological instrument and guide the instrumentthrough the hole. The guide tube also includes an expansion mechanismthat includes a plurality of sections that are slidably attached to atapered portion of an exterior surface of the cannula member. Theplurality of sections are operable to slide on the tapered portion ofthe exterior surface to thereby move radially relative to the axisbetween a retracted position and an expanded position. The guide tubealso includes a biasing member that is operably coupled to each of theplurality of sections to bias the plurality of sections toward the axisto bias the plurality of sections toward the retracted position.Furthermore, the guide tube includes a retaining mechanism that isthreadably attached to the cannula member. The retaining mechanism isoperable to threadably advance relative to the cannula member to slidethe plurality of sections along the tapered portion of the exteriorsurface of the cannula member to move the plurality of sections towardthe expanded position. The retaining mechanism is also operable toretain the plurality of sections in the expanded position to engage withthe inner surface of the hole.

Further areas of applicability will become apparent from the descriptionprovided herein. The description and specific examples in this summaryare intended for purposes of illustration only and are not intended tolimit the scope of the present disclosure.

DRAWINGS

The drawings described herein are for illustrative purposes only ofselected embodiments and not all possible implementations, and are notintended to limit the scope of the present disclosure.

FIG. 1 is an isometric view of a guide tube according to variousexemplary embodiments of the present disclosure;

FIG. 2 is a section view of the guide tube taken along the line 2-2 ofFIG. 1 ;

FIG. 3 is an enlarged section view of a distal portion of the guide tubetaken along line 3-3 of FIG. 2 ;

FIG. 4 is a section view of the guide tube taken along line 4-4 of FIG.2 shown partially inserted in a bore hole within a patient, wherein anexpansion member is shown in a retracted position; and

FIG. 5 is a section view of the guide tube taken along line 5-5 of FIG.2 , wherein the expansion member is shown in an expanded position andengaged with an inner surface of the bore hole.

Corresponding reference numerals indicate corresponding parts throughoutthe several views of the drawings.

DETAILED DESCRIPTION

Example embodiments will now be described more fully with reference tothe accompanying drawings.

Referring initially to FIG. 1 , a guide tube 10 (i.e., guide tool) isillustrated according to various exemplary embodiments of the presentdisclosure. The guide tube 10 can generally include a cannula member 12defining a passage 14 extending therethrough along a longitudinal axisX. The guide tube 10 can also include a handle member 16 and anexpansion member 18 (expansion mechanism) that are operably coupled toopposite ends of the cannula member 12. The expansion member 18 can bemoveably coupled to the cannula member 12 to move radially between aretracted position (FIG. 4 ) and an expanded position (FIG. 5 ) relativeto the axis X of the cannula member 12. The guide tube 10 can furtherinclude a biasing member 20 that biases the expansion member 18 towardthe retracted position or the expanded position. Furthermore, the guidetube 10 can include a retaining mechanism 22 that can selectively movethe expansion member 18 against the biasing load supplied by the biasingmember 20, and the retaining mechanism 22 can retain the expansionmember 18 in at least one of the retracted and expanded positions.

Thus, as shown in FIGS. 4 and 5 , the guide tube 10 can be used toselectively engage with and disengage from a surface 26 (e.g., an innerdiameter surface) of a burr hole 24 formed within tissue 28 (e.g., skin,fat, cranial or other bone tissue, etc.). The burr hole 24 can be formedto have a substantially constant width (e.g., diameter) along its axiallength (i.e., the hole 24 can be non-tapered).

During use, the expansion member 18 can be moved to the retractedposition (FIG. 4 ) to have a smaller width than the hole 24 such thatthe guide tube 10 can be partially inserted into the hole 24 and/orremoved from the hole 24. Also, the expansion member 18 can be moved tothe expanded position (FIG. 5 ) to engage with the inner surface 26 andto fix the expansion member 18 in position relative to the tissue 28. Inthis position, the passage 14 in the cannula member 12 can be alignedwith the hole 24 in the tissue 28, and an instrument 30 (e.g., aneurological probe 30, etc.) can be moved through the passage 14 of thecannula member 12 along the axis X to move into and out of the hole 24in the tissue 28. The cannula member 12 can guide this movement of theprobe 30 such that the probe 30 moves along a desired trajectory towardand away from a target T within the body.

Various embodiments of the guide tube 10 will now be discussed indetail. Although the guide tube 10 is described in connection withneurological procedures, it will be appreciated that the guide tube 10could be used in connection with any other medical procedure withoutdeparting from the scope of the present disclosure.

As shown in FIGS. 1-3 , the cannula member 12 can be hollow and tubularwith a proximal end 32 and a distal end 34. The passage 14 can extendcontinuously from the proximal end 32 to the distal end 34. The axis Xcan be substantially straight as shown, or the axis X could be curved insome embodiments. Moreover, in some embodiments, the curvature of thepassage 14 could be adjustable due to the construction of the cannulamember 12 and/or other portions of the guide tube 10.

The passage 14 can be defined by an inner surface 36, and the innersurface 36 can have a substantially constant diameter for the majorityof its longitudinal length. Also, in some embodiments, the inner surface36 can be tapered along its length.

As shown in FIG. 1 , the cannula member 12 can further include anexterior surface 31 having a proximal portion 33, a distal portion 35,and an intermediate portion 29. In some embodiments, the proximalportion 33 of the exterior surface 31 can have a constant width (e.g.,diameter) along its axial length. The distal portion 35 can include atleast one tapered surface 37 that tapers in width along its axiallength. The intermediate portion 29 can be threaded (i.e., can includean outer threading 43).

In some embodiments, the distal portion 35 of the exterior surface 31 ofthe cannula member 12 can include one or more exterior grooves 45 (FIGS.1 and 2 ). The grooves 45 can extend axially (i.e., longitudinally) onthe cannula member 12 and can be spaced apart about the axis X (FIG. 2). In the embodiments shown in FIG. 2 , there are three grooves 45evenly spaced apart by 120 degrees about the axis X, but there can beany number of grooves 45 at any angular spacing. The depth of eachgroove 45 can change gradually along its axial length to define thetapered surface 37. More specifically, the groove 45 can be deeper at aproximal end 39 than at a distal end 41. Thus, the tapered surface 37can be tapered at an acute angle α relative to the axis X (FIG. 3 ). Thetapered surface 37 can be tapered at any angle α (e.g., approximatelythree degrees). Also, the tapering of the surface 37 could be such thata distal radius R1 at the distal end 41 is greater than a proximalradius R2 at the proximal end 39.

Furthermore, the cannula member 12 can include one or more shoulders 47(FIGS. 3-5 ). The shoulder(s) 47 can be defined at the proximal end 39of the respective groove 45. As will be discussed, the shoulders 47 canlimit movement of the expansion member 18 relative to the cannula member12.

Exemplary embodiments of the handle member 16 of the guide tube 10 areshown in FIGS. 1, 4, and 5 . The handle member 16 can include an upperplate 38 and an attachment portion 40 that are integrally attached. Theattachment portion 40 can be hollow and tubular and can be fixed to theproximal end 32 of the cannula member 12. The upper plate 38 can be flatand disc-shaped and can extend perpendicularly from the axis X. Theupper plate 38 can also include one or more recesses 44. The recesses 44can be contoured and spaced about the axis X for improved handling ofthe guide tube 10. Additionally, the handle member 16 can include anopening (e.g., a through hole) that is centered over the proximal end 32of the passage 14.

Referring to FIGS. 1, 2, and 3 , the expansion member 18 will bediscussed in greater detail. The expansion member 18 can include aplurality of sections 46 a, 46 b, 46 c. In the illustrated embodiments,there are three sections 46 a, 46 b, 46 c, but there can be any numberof sections 46 a, 46 b, 46 c. Each section 46 a, 46 b, 46 c can beelongate and can include an outer surface 48 and an inner surface 50.The inner surface 50 can include a rail 52 (FIG. 2 ) that is receivedwithin a respective groove 45 of the cannula member 12. Thus, the rail52 can be tapered relative to the axis X, similar to the respectivegroove 45. Also, as shown in FIG. 2 , the sections 46 a, 46 b, 46 c canbe spaced apart circumferentially about the axis X. The outer surface 48of the sections 46 a, 46 b, 46 c can be substantially smooth or can havea rough texture (e.g., small spikes, knobs, etc.) for engaging the innersurface 26 of the hole 24. However, the outer surface 48 of the sections46 a, 46 b, 46 c can extend substantially parallel to the axis X.

The rails 52 of the sections 46 a, 46 b, 46 c can axially slide intandem on the tapered surface 37 of the grooves 45 of the cannula member12. While sliding, the sections 46 a, 46 b, 46 c can move simultaneouslyin the axial and radial directions for moving between the expandedposition (FIG. 5 ) and the retracted position (FIG. 4 ). Specifically,when moving from the retracted position to the expanded position, thesections 46 a, 46 b, 46 c can move toward the distal end 34 and radiallyoutward away from the axis X. In contrast, when moving from the expandedposition to the retracted position, the sections 46 a, 46 b, 46 c canmove toward the proximal end 32 and radially inward toward the axis X.Because the rails 52 move within the respective grooves 45, this slidingmovement can be very smooth and controlled.

It will be appreciated also that the sections 46 a, 46 b, 46 c couldinclude the grooves 45 and the cannula member 12 can include the rails52 without departing from the scope of the present disclosure.Furthermore, it will be appreciated that the grooves 45 and rails 52could be interconnected via a dovetail or otherwise keyed againstrotation about the axis X.

The inner surface 50 of the sections 46 a, 46 b, 46 c can also includean abutment wall 49 (FIGS. 3-5 ) that abuts against the respectiveshoulder 47 of the cannula member 12, for instance, when the sections 46a, 46 b, 46 c are in the fully retracted position (FIG. 4 ). Thisabutment can limit the movement of the sections 46 a, 46 b, 46 c alongthe axis X toward the proximal end 32.

Furthermore, the sections 46 a, 46 b, 46 c can also include an exteriorshoulder 51. The exterior shoulder 51 can be rounded about the axis X.In some embodiments, the width of the guide tube 10 measured at theexterior shoulders 51 can be greater than the width of the burr hole 24(FIGS. 4 and 5 ), to thereby limit movement of the guide tube 10 intothe burr hole 24.

In addition, the sections 46 a, 46 b, 46 c can each include a groove 54(FIGS. 1 and 3-5 ). The grooves 54 can extend circumferentially acrossthe sections 46 a, 46 b, 46 c.

The biasing member 20 can be seen most clearly in FIGS. 1 and 3-5 . Thebiasing member 20 can be a resiliently elastic O-ring that is receivedwithin the grooves 54 of the sections 46 a, 46 b, 46 c of the expansionmember 18. Positioned as such, the biasing member 20 can remain inresilient tension such that the biasing member 20 biases the sections 46a, 46 b, 46 c radially toward the axis X. Because of the tapered surface37, the biasing member 20 also biases the sections 46 a, 46 b, 46 ctoward the retracted position.

The retaining mechanism 22 can include a hollow tubular section 56 and ahandle section 58 that extends perpendicularly from the tubular section56. The tubular section 56 can receive the cannula member 12.Specifically, the tubular section 56 can include interior threading 62that is threadably engaged with the threading 43 of the cannula member12. The tubular section 56 can also include a cuff 57 that receives andoverlaps the proximal, exterior end of the sections 46 a, 46 b, 46 c.

As shown in FIGS. 3, 4, and 5 , the cuff 57 can include an annularprojection 59 that extends radially inward toward the axis X. Theprojection 59 can be received within a corresponding annular notch 61formed within the sections 46 a, 46 b, 46 c to interconnect theretaining mechanism 22 and ensure tandem movement of the retainingmechanism 22 and sections 46 a, 46 b, 46 c as will be discussed. It willbe appreciated that the sections 46 a, 46 b, 46 c could include theprojection 59 while the retaining mechanism 22 could include the notch61 without departing from the scope of the present disclosure.

The retaining mechanism 22 can be rotated and threadably advanced ineither direction parallel to the axis X. The handle section 58 caninclude one or more curved recesses 60 that facilitate rotation of theretaining mechanism 22 about the axis X.

As shown in FIGS. 3-5 , when the retaining mechanism 22 is threadablyadvanced toward the distal end 34 of the cannula member 12, a distalabutment surface 64 of the retaining mechanism 22 pushes against aproximal end 66 of the sections 46 a, 46 b, 46 c parallel to the axis X.This causes the sections 46 a, 46 b, 46 c to slide along the taperedsurface 37 to move both parallel to the axis X toward the distal end 34and radially outward toward the expanded position. The threadedengagement between the retaining mechanism 22 and the cannula member 12can also allow the retaining mechanism 22 to hold the sections 46 a, 46b, 46 c in the expanded position (or in any intermediate positionbetween the expanded and retracted positions) against the biasing forcesupplied by the biasing member 20. Also, when the retaining mechanism 22is threadably advanced toward the proximal end 32 of the cannula member12, the tension in the biasing member 20 can cause the sections 46 a, 46b, 46 c to move parallel to the axis X toward the proximal end 32 and tomove radially inward toward the retracted position. The abutment walls49 of the sections 46 a, 46 b, 46 c can abut against the shoulders 47 tolimit axial movement of the sections 46 a, 46 b, 46 c as shown in FIG. 4.

Accordingly, the guide tube 10 can be used, for instance, to guidemovement of a neurological probe 30 (FIG. 5 ) or other similar devicetoward and away from a target T within the patient's body (e.g., thepatient's brain). First, the hole 24 can be formed within the cranialbone or other tissue 28 (FIG. 4 ). The hole 24 can be formed such that acenterline C of the hole 24 intersects the target T. In someembodiments, the hole 24 can be circular in shape and can have adiameter of six millimeters (6 mm) to ten millimeters (10 mm); however,the hole 24 can have any suitable shape and dimensions.

Then, assuming that the sections 46 a, 46 b, 46 c of the expansionmember 18 are positioned in the retracted position (FIG. 4 ), thesections 46 a, 46 b, 46 c and the distal end 34 of the cannula member 12can be inserted into the hole 24 such that the proximal end 32 of thecannula member 12 projects therefrom. In some embodiments, the shoulder51 abuts against the tissue 28 surrounding the hole 24 to limit movementof the guide tube 10 into the hole 24.

Then, the retaining mechanism 22 can be threadably advanced to move thesections 46 a, 46 b, 46 c of the expansion member 18 toward the expandedposition, and the outer surfaces 48 of the sections 46 a, 46 b, 46 c canengage with the inner surface 26 of the hole 24. Thus, the guide tube 10can be fixed relative to the cranial tissue 28, the axis X can besubstantially aligned with the centerline C of the hole 24, and the axisX can intersect the target T within the patient.

It will be appreciated that the outer surface 48 of each section 46 a,46 b, 46 c can remain substantially parallel to the axis X as thesections 46 a, 46 b, 46 c move toward the expanded position. Since thehole 24 can have a substantially constant width along its axis C, theouter surfaces 48 of the sections 46 a, 46 b, 46 c can engage arelatively large surface area of the inner surface 26 of the hole 24.Stated differently, the outer surfaces 48 of the sections 46 a, 46 b, 46c can have surface contact (as opposed to point contact) with the innersurface 26 of the hole 24. As such, the sections 46 a, 46 b, 46 c of theexpansion member 18 can distribute forces substantially evenly to thetissue 28, the guide tube 10 is likely to be very stable when engagedwith the tissue 28, and the guide tube 10 is unlikely to fracture orotherwise damage the tissue 28 when engaging the tissue 28.

Next, as shown in FIG. 5 , the probe 30 can be inserted within thepassage 14, and the inner surface 36 of the passage 14 can help guidethe probe 30 as it moves along the axis X toward the probe. After theprocedure is completed, the probe 30 can be moved in a reverse directionalong the axis X and withdrawn from the guide tube 10. Then, thesections 46 a, 46 b, 46 c can be moved to the retracted position, andthe guide tube 10 can be removed from the hole 24.

As shown schematically in FIGS. 3, 4, and 5 , the guide tube 10 caninclude a tracking sensor 71 that can track the position and/ororientation of the guide tube 10 relative to the patient and/or theprobe 30. (The tracking sensor 71 is represented schematically by aboxed “S”.) For instance, the tracking sensor 71 can be operable fortracking the position and/or orientation of the passage 14 within thecannula member 12 relative to the patient. Although the tracking sensor71 is shown included on the cannula member 12, the tracking sensor 71can be included on one or more of the sections 46 a, 46 b, 46 c of theexpansion member 18, the retaining mechanism 22, or any other portion ofthe guide tube 10. The tracking sensor 71 can include features taught inthe commonly-owned U.S. patent application Ser. No. 11/739,401 filedApr. 24, 2007, U.S. patent application Ser. No. 12/103,488, filed Apr.15, 2008, U.S. patent application Ser. No. 12/239,114, filed Sep. 26,2008, and/or U.S. patent application Ser. No. 12/770,181, filed Apr. 29,2010, each of which is hereby incorporated by reference in its entirety.The tracking sensor 71 can be a coil of conductive material or anotherinstrument that transmits and/or receives electromagnetic signalsaccording to the position and/or orientation of the guide tube 10. Thetracking sensor 71 can also be an optical transmitter, reflector,receiver, or another instrument that transmits and/or receives opticalsignals corresponding to the position and/or orientation of the guidetube 10. The tracking sensor 71 can also employ combinations of theseand other tracking technologies. Also, the tracking sensor 71 canoperatively communicate with a corresponding sensor 73 that is attachedto the probe 30 (FIG. 5 ). Moreover, the tracking sensor 73 can detectthe trajectory of the probe 30, the amount of distance the probe 30 hasmoved toward and/or away from the guide tube 10, the amount of distancethe probe 30 has moved into and/or out of the patient's body, etc.

Other variations of the guide tube 10 are within the scope of thepresent disclosure. For instance, although the axis X is at a fixedorientation relative to the sections 46 a, 46 b, 46 c of the expansionmember 18 in the embodiments discussed above, the guide tube 10 could beconfigured such that the orientation of the axis X can be variedrelative to the expansion member 18 in other embodiments. In the lattercase, the guide tube 10 could be engaged with the inner surface 26 ofthe hole 24 as discussed above, and then the cannula member 12 could beselectively rotated, bent, or otherwise repositioned to reorient theaxis X relative to the expansion member 18 and the hole 24. Forinstance, the guide tube 10 could include multiple sections that areattached by a gimbaled joint, ball-and-socket joint, etc., and thesections could be pivoted relative to each other to reorient the axis X.As such, even if the centerline C of the hole 24 is out of alignmentwith the target T, then the axis X of the cannula member 12 can beselectively oriented toward the target T. Also, if there are severaltargets T that can be accessed through one hole 24, the guide tube 10can remain in the same position on the cranial tissue 28 to access eachof the targets T.

It will also be appreciated that the guide tube 10 could be made out ofany suitable materials. For instance, in some embodiments, one or moreof the components of the guide tube 10 are made out of a polymericmaterial (e.g., injection molded plastic). As such, the guide tube 10could be intended for one-time use (i.e., can be disposable). In otherembodiments, one or more components could be made of metal, and theguide tube 10 could be intended for multiple uses. In the latter case,the guide tube 10 can be sterilized between uses (e.g., in anautoclave).

In summary, the guide tube 10 can be attached and detached from thepatient in a very convenient manner. Also, the guide tube 10 canaccurately guide the instrument 30 toward the desired target T withinthe patient despite the hole 24 having a relatively small width.

The foregoing description of the embodiments has been provided forpurposes of illustration and description. It is not intended to beexhaustive or to limit the disclosure. Individual elements or featuresof a particular embodiment are generally not limited to that particularembodiment, but, where applicable, are interchangeable and can be usedin a selected embodiment, even if not specifically shown or described.The same may also be varied in many ways. Such variations are not to beregarded as a departure from the disclosure, and all such modificationsare intended to be included within the scope of the disclosure.

What is claimed is:
 1. A method for engaging a guide tube with a surface of a hole formed in tissue of a patient, the guide tube including a cannula member defining a passage extending therethrough along an axis, the guide tube also including an expansion member having a distal end that is movably coupled to the cannular member to selectively move the distal end radially between a retracted position and an expanded position relative to the axis of the cannula member, the method comprising: forming the hole in the tissue, such that a center line of the hole along the axis intersects to a target; inserting the guide tube into the hole while the expansion member is in the retracted position; selectively moving the distal end of the expansion member from the retracted position to the expanded position to engage the distal end of the expansion member with the surface of the hole; and inserting an instrument into the passage and guiding the instrument toward the target along the axis.
 2. The method of claim 1, further comprising advancing the guide tube into the hole until a shoulder of the guide tube buts against the tissue surrounding the hole to limit movement of the guide tube into the hole.
 3. The method of claim 1, further comprising biasing the expansion member to a retracted position.
 4. The method of claim 1, wherein a distal end of the cannula member includes a tapered exterior surface and the distal end of the expansion member includes a tapered interior surface, wherein selectively moving the expansion member further includes sliding the tapered interior surface of the expansion member along the tapered exterior surface of the cannula member such that an outer distal surface of the expansion member stays substantially parallel to the axis upon being moved from the retracted position to the expanded position.
 5. The method of claim 1, further comprising threadably rotating a retaining mechanism coupled to the cannula member to move the expansion member from the retracted position to the expanded position.
 6. The method of claim 1, further comprising tracking a position and orientation of the guide tube relative to the patient using a tracking sensor associated with the guide tube.
 7. The method of claim 1, further comprising moving an outer distal surface of the expansion member substantially parallel to the axis from the retracted position to the expanded position.
 8. The method of claim 1, further comprising forming a surface contact of an outer distal surface of the expansion member with the surface of the hole when the expansion member moves from the retracted position to the expanded position.
 9. The method of claim 1, wherein inserting the instrument into the passage includes inserting a neurological probe into a brain of a patient.
 10. The method of claim 1, further comprising detecting a trajectory of the instrument using a tracking sensor associated with the instrument.
 11. The method of claim 1, further comprising determining an amount of distance the instrument has moved toward the target using a tracking sensor associated with the instrument.
 12. The method of claim 1, further comprising changing the orientation of the axis of the cannula relative to the expansion member and hole.
 13. The method of claim 12, further comprising orienting the axis of the cannula to an additional target extending along a reoriented axis.
 14. The method of claim 1, further comprising tracking a position of the guide tube with a tracking sensor associated with the guide tube and tracking a position of the instrument with a tracking sensor associated with the instrument.
 15. A method for engaging a guide tube with a surface of a hole formed in tissue of a patient, the guide tube including a cannula member defining a passage extending therethrough along an axis, the guide tube also including an expansion member that is movably coupled to the cannular member, the expansion member having a proximal end and a distal end, the distal end is configured to selectively move radially outward between a retracted position and an expanded position relative to the axis of the cannula member, the method comprising: forming the hole in the tissue; inserting the guide tube into the hole while the expansion member is in the retracted position; selectively moving the distal end of the expansion member radially outward from the retracted position to the expanded position to engage the distal end of the expansion member with the surface of the hole; and inserting a probe into the passage.
 16. The method of claim 15, further comprising simultaneously moving the distal end of the expansion member distally and radially outward from the axis.
 17. The method of claim 16, further comprising moving an outer surface of the distal end of the expansion member substantially parallel to the axis from the retracted position to the expanded position.
 18. The method of claim 15, wherein inserting the probe into the passage includes inserting a neurological probe into a brain of the patient.
 19. A method for engaging a guide tube with a surface of a hole formed in tissue of a patient, the guide tube including a cannula member defining a passage extending therethrough along an axis, the guide tube also including an expansion member that is movably coupled to the cannular member to selectively move between a retracted position and an outward expanded position relative to the axis of the cannula member, the method comprising: forming the hole in the tissue; inserting a distal end of the guide tube into the hole while the expansion member is in the retracted position; engaging a shoulder of the guide tube against the tissue surrounding the hole to limit movement of the guide tube into the hole; threadably advancing a retaining mechanism relative to the cannula member to selectively move a distal end of the expansion member from the retracted position to the expanded position to engage the expansion member with the surface of the hole; and inserting a probe into the passage and guiding the probe along the axis.
 20. The method of claim 19, wherein forming the hole in the tissue includes forming a hole within a cranial bone; and inserting the probe into the passage includes inserting a neurological probe into the brain of the patient. 